Different between const int * , int const * and int * const

* Question: 

What different between const int * , int const * , int * const ?

* Answer: 

• int*                                                           - pointer to int
• const int * == int const *                     - pointer to const int
• int * const - const pointer to int
• const int * const == int const * const - const pointer to const int

• int **                       - pointer to pointer to int
• int ** const             - a const pointer to a pointer to an int
• int * const *           - a pointer to a const pointer to an int
• int const **            - a pointer to a pointer to a const int
• int * const * const - a const pointer to a const pointer to an int

* Reference: 

http://stackoverflow.com/questions/1143262/what-is-the-difference-between-const-int-const-int-const-int-const

Difference between std::thread and pthread

* Question: 

What are the differences between std::thread and pthread

* Answer: 

The std::thread library is implemented on top of pthreads in an environment supporting pthreads 

std::thread provides portability across different platforms like Windows, MacOS, and Linux, but may not be complete on all platforms yet.

The C++11 std::thread class unfortunately doesn't work reliably (yet) on every platform, even if C++11 seems available.

* Reference: 

http://stackoverflow.com/questions/13134186/c11-stdthreads-vs-posix-threads

Difference between size_t and std::size_t

* Question: 

What are the differences between size_t and std::size_t

* Answer: 

C's size_t and C++'s std::size_t are both same.

In C, it's defined in <stddef.h> and in C++, its defined in <cstddef> whose contents are the same 

as C header (see the quotation below). Its defined as unsigned integer type of the result of the 

sizeof operator.

* Reference: 

http://stackoverflow.com/questions/5813700/difference-between-size-t-and-stdsize-t